Elective CT Scan vs. MRI: Which Should You Choose?

ct scan vs mri: older man looking at camera

Key takeaways:

  • When comparing CT scans vs. MRIs, note that both can help identify cancer as well as other illnesses.
  • MRIs better evaluate the flow of bodily fluids, provide better soft-tissue contrast, and can image tissue near bones.
  • CT scans are preferred for identifying specific cancers, such as lung, liver, and pancreas, but CT scans expose you to ionizing radiation.
  • Both scans are painless, non-invasive, and proactive ways to protect your health.

While doctors sometimes order an MRI scan (magnetic resonance imaging) or a CT Scan (computed tomography) to help diagnose a medical illness or condition, it’s nice to know that we can take control over our own health by electing to have preventative scans on an annual basis. It’s important to understand the differences between a CT scan vs. MRI.

Oncologists, in particular, often use these types of diagnostic imaging to find and stage cancer.

A CT scan uses multiple X-rays to create detailed pictures of organs, bones, and other soft tissues.

The pictures are used to create three-dimensional images that can reveal abnormalities.

Magnetic resonance imaging (MRI) also creates detailed pictures but instead of ionizing radiation, it uses a powerful magnet and radio waves to generate the internal images of your body.

Similarly, these pictures can show the difference between normal and diseased tissues.

What are the differences between a CT scan vs. MRI?

MRI scans and CT scans provide more detail and higher resolution images than X-rays, ultrasound, or PET scans.

A positron emission tomography, also known as a PET scan, might be used to see how your organs and tissues are working. A PET scan uses a radioactive drug (tracer) to let your doctor see what is happening inside your body.

While an X-ray can be used to examine most parts of the body, X-ray images are normally used to detect joint or bone fractures in the skeletal system.

Ultrasound utilizes high-frequency sound waves, which bounce off internal organs to create images of the body’s inside. Ultrasound is safe for pregnant women and fetuses.

Other reasons for a radiology scan might include torn ligaments, arthritic conditions or degenerative disk disease, traumatic brain injury, bone density, as well as other soft tissue issues.

Your doctor will make diagnostic imaging recommendations to your radiologist based on your symptoms.

If your doctor suspects an aneurysm, brain tumor, breast cancer, cancer of the pancreas, or cancer in another part of the body, they may order a CT scan vs. MRI scan.

An MRI is more likely to be indicated if a detailed image of tissues, the spinal cord, ligaments, bones, or organs is necessary.

If a general image is necessary a computed tomography or CT scan is more likely to be ordered, mostly because CT scans are more cost-effective.

Both MRI scans and CT scans can be used to determine the best biopsy site to get a definitive diagnosis of cancer.

Either scan can give your oncologist a clearer picture of where cancer has spread in your body.

MRI scans explained.

ct scan vs mri: imaging equipment

Magnetic resonance imaging (MRI) scans provide a detailed image without the use of X-rays or ionizing radiation, and they’re non-invasive.

MRIs are large machines that are shaped like an elongated doughnut and use radio waves and strong magnets to see the bones, tissues, and organs of your body. An MRI machine creates a strong magnetic field and uses radio frequencies that bounce off your fat and water molecules. The radio waves go to a receiver that creates an image that can show abnormalities in bone and in soft tissues.

MRI scans are seldom used for “whole body” images, mostly because MRI scans are relatively expensive. Instead, MRI scans generally focus on particular areas such as your joints, cardiovascular system, breasts, or brain.

MRI machines are noisy and usually enclosed. Patients who suffer from claustrophobia may have a hard time lying still in the machine for extended periods of time. In this case, an open MRI or sedation could be the answer. If you suffer from claustrophobia or anxiety in tight spaces, tell your technologist.

Scans can last from 30 minutes to an hour, and some people are bothered by the loud noise. The technician will likely offer you headphones and a chance to listen to your favorite music or audiobook.

You will have to lie still during the scan.

MRI scans offer many benefits:

  • An MRI provides better soft tissue contrast than a CT scan.
  • An MRI can help evaluate the flow of blood and other fluids, organ contractions, and relaxation.
  • An MRI can image tissues surrounded by bone, such as the spine.
  • Unlike a CT scan, MRI scans do not use ionizing radiation

Are MRI scans safe?

The short answer is, yes, an MRI scan is usually safe and non-invasive.

An MRI could be unsafe for patients with metal implants that are not MRI-safe, pacemakers, insulin pumps, or other medical devices..The radiofrequency, along with the magnetic fields, can cause implant devices to heat up. This could result in burns on the tissue surrounding your implant.

CT scans explained.

White MRI machine

Sometimes called a CAT scan, a CT scan, or computed tomography, this scan is able to target a particular area, or it can be a whole-body scan.

Your doctor may order the scan with or without contrast. Contrast uses a dye to define organs or blood vessels.

Like an MRI machine, a CT scanner is a doughnut-like shaped machine. However, it’s shorter and more open than an MRI machine.

Like in an MRI scan, you’ll lie on a table that slides through the “hole,” and you’ll need to lie still.

A CT scan uses multiple X-rays that arc through your body at different angles.

Different body parts create variations in exposure, and the computer constructs a 3-D image. The X-ray apparatus inside of a CT scanner can see hundreds of degrees of tissue density, which allows for detailed images of internal organs.

Oncologists overwhelmingly prefer computed tomography for making a clinical diagnosis of several types of cancers, such as lung cancer, liver cancer, and cancer in the pancreas. The scan provides detailed information about the size of the tumor, where it’s located, and if cancer has spread.

Low-dose vs. normal-dose CT scans 

The primary difference between low-dose CT scans and normal CT scans is the amount of radiation emitted. A low-dose scan emits five times less radiation than a normal or standard-dose CT scan.

Low-dose scans are mostly used on people with a very high risk of developing lung cancer or on patients who already have lung cancer.

Are CT scans safe?

CT scans are non-invasive, but they use ionizing radiation to create internal images of the body. Before getting a CT scan, you should speak to a medical provider to understand the risks and benefits of a CT scan. A CT scan can improve diagnoses, limit unneeded medical procedures, and enhance overall treatment efficacy. Computed tomography images bone, soft tissue, and blood vessels all at the same time.

People at high risk for lung cancer should only have a low-dose CT scan to minimize exposure to ionizing radiation.

Radiation can also be harmful to unborn babies. Therefore, pregnant women should not have CT scans.

A CT scan with contrast may pose a problem for people who are allergic to the contrast material and for people with kidney problems.

The importance of screening with a CT scan vs. MRI scan for cancer prevention.

Senior woman looking straight ahead

Preventive medicine can provide early detection of disease, lead to more successful treatment, and avert complications.

According to a study done by the Canary Foundation, your chances of surviving cancer are greater if it is diagnosed when it is still confined to the organ of origin (stage I). Survival rates decline as tumors enlarge and spread regionally (stages II, III) or distantly (stage IV).

In most cases, your doctor will recommend the test that is right for your suspected condition. Alternatively, you may choose to have periodic screenings as a preventative measure.

According to cancer screening guidelines, it is recommended that screening is done for colon cancer, lung cancer, breast, and uterine cancer; however, most other types of cancer do not currently have recommendations.

At Ezra, we created a full-body MRI scan, which screens for cancer and pre-cancer warning signs in fourteen different organs, including the brain, spine, liver, gallbladder, and pancreas among others.

Scheduling an elective MRI scan or CT scan without a doctor’s order.

Early detection is the best defense against cancer.

In most cases, your doctor will order an MRI or a CT scan to help diagnose or evaluate you for a specific illness or condition. However, more people are choosing to undergo an elective MRI or CT scan without a doctor referral.

At Ezra, our team of medical providers will review your medical information and provide you with the referral prescription to get the scan you need.

As a preventative measure, you can elect to schedule an MRI or CT scan on an annual basis, giving you more control over your own health and wellbeing.